Antigen-binding receptors from T lymphocytes are isolated using as primary approach anti-idiotypic antibodies. Such receptors will be defined as to biochemistry, serology, genetics and function. Use will be taken of such receptors in "pure" form to obtain specific auto-anti-idiotypic antibodies leading to selective immunosuppression in adult, immunocompetent individuals. BIBLIOGRAPHIC REFERENCES: Binz, H., Wigzell, H., and Bazin, H. T-cell idiotypes are linked to immunoglobulin heavy chain genes. Nature, 264:639, 1976. Binz, H., and Wigzell, H. Specific transplantation tolerance induced by autoimmunization against the individual's own, naturally occurring idiotypic, antigen-binding receptors. J. Exp. Med., 144:1438, 1976.